1. Field of Invention
This invention relates to an electric battery charger.
2. Description of the Prior Art
When a battery is charged up to what is referred to as a basic charged condition, it is about 85% charged and the individual cells may be at different charged levels. It is desirable to apply a finish or equalization charge to the battery which is intended to bring each cell of the battery up to a 100% charged condition. Conventional battery chargers attempt to attain a fully charged condition in various ways.
Conventional electric battery chargers are of three general types. There is a simple unregulated taper charger. The finish charge of the battery is not regulated with respect to the line voltage. There is no regulation and no automatic shut off.
There is a so-called automatic battery charger which is like a taper charger except as the battery voltage approaches its high finish value, the finish charger or voltage is limited to a preset value such that possible damage to a battery will be reduced. The finish voltage will be constant and at its proper setting for the general type of battery being charged but not necessarily for the particular condition of the battery.
The third type of conventional battery charger is a deep cycle charger having an electric timer to be set manually by the user to bring the battery to what the user believes will be a full charge and to include an adequate equalization charge. This is a mechanical timer and it does not sense when the equalization charge begins and whether the timer has been set correctly.
With this third type of battery charger, if the battery is more discharged than thought to be, the total time for the charge and equalization charge will be insufficient to equalize the charge within the battery. If the timer is set for too long a time, the total charge will be excessive causing water in the battery to become decomposed and often also leading to corrosion of the electrodes.
It is desirable to have a timing apparatus included in a battery charger such that the equalization timer does not turn on until the basic charge is completed and then the equalization charging time is set precisely for the equalization or finish charge.